Effects of different durations of fasting/re-feeding bouts on growth, biochemical and histological changes in the digestive tract of Gansu golden trout (Oncorhynchus mykiss)

This study was conducted to explore the outcomes of starvation/re-feeding techniques on growth performance, liver antioxidant activities, and histological changes of the gastrointestinal organs of Gansu golden trout. A total of 225 juveniles were divided into 5 treatment groups; the control group (N0) was routinely fed every day while the other groups (N7, N14, N21, and N28) were starved for 7, 14, 21, and 28 days, respectively and after the starvation session, each group was re-fed for 28 days. Compensatory growth was statistically recorded in N14. Weight gain rate and feeding ratio were the highest in the N14 group, while specific growth rate and feeding conversion ratio showed significant increases in the fish groups exposed to longer starvation periods. Liver antioxidant activities showed a significant increase and decrease in malondialdehyde and superoxide dismutase levels in N21 and N28, respectively, which returned to normal levels after re-feeding. Stomach, intestine, and liver showed histological alterations in all groups and the severity was correlated with the fasting periods. Those changes were restored to a certain degree after feeding was resumed. The compensation by group N14 presents potential for economic usefulness of the fasting/re-feeding strategy in Gansu golden trout.